Since you have a German shepherd dog MIX, I see no point in letting her have a heat. Please spay her BEFORE her heat. If you let her go through her heat, her chances of cancer are so much greater. She can also get pyometra and die. My German shepherd died of cancer because my dad didn't spay her before her first heat.

Besides improving her health, spaying her will make her less aggressive, and more well-behaved. She will not try to run away to find a mate, she will not get pregnant, she will eat less food, etc. Do not let her become a sexually frustrated dog who will take out her frustrations in destructive or aggressive ways. Spay her and she will be so much healthier and happier.